2-32126960-C-A

Variant names:

• chr2-32126960-C-A
• rs1060499670
• NM_014946.4:c.1111C>A

Variant summary

Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PM1 PM2 PM5 PP2

The NM_014946.4(SPAST):​c.1111C>A​(p.Leu371Ile) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000686 in 1,457,846 control chromosomes in the GnomAD database, with no homozygous occurrence. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. L371R) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: SPAST NM_014946.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 7.37
• Publications: 0 publications found

Genes affected

SPAST (HGNC:11233): (spastin) This gene encodes a member of the AAA (ATPases associated with a variety of cellular activities) protein family. Members of this protein family share an ATPase domain and have roles in diverse cellular processes including membrane trafficking, intracellular motility, organelle biogenesis, protein folding, and proteolysis. The use of alternative translational initiation sites in this gene results in a single transcript variant that can produce isoforms that differ in the length of their N-terminus and which thereby differ in the efficiency of their export from the nucleus to the cytoplasm. In addition, alternative splicing results in multiple transcript variants that encode isoforms that differ in other protein regions as well. One isoform of this gene has been shown to be a microtubule-severing enzyme that regulates microtubule abundance, mobility, and plus-end distribution. Mutations in this gene cause the most frequent form of autosomal dominant spastic paraplegia 4. [provided by RefSeq, May 2018]

SPAST Gene-Disease associations (from GenCC):

• hereditary spastic paraplegia 4

  Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae), Illumina, Genomics England PanelApp, Ambry Genetics
• Charlevoix-Saguenay spastic ataxia

  Inheritance: AR Classification: DEFINITIVE Submitted by: G2P
• neurodevelopmental disorder

  Inheritance: AD Classification: STRONG Submitted by: G2P
• SPAST-related motor disorder

  Inheritance: AR Classification: STRONG Submitted by: Ambry Genetics

ACMG classification

Our verdict: Likely_pathogenic. The variant received 7 ACMG points.

• PM1: In a hotspot region, there are 12 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 7 uncertain in NM_014946.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr2-32126961-T-G is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 432721.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 148 curated pathogenic missense variants (we use a threshold of 10). The gene has 21 curated benign missense variants. Gene score misZ: 1.2438 (below the threshold of 3.09). Trascript score misZ: 0.22274 (below the threshold of 3.09). GenCC associations: The gene is linked to hereditary spastic paraplegia 4, SPAST-related motor disorder, Charlevoix-Saguenay spastic ataxia, neurodevelopmental disorder.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SPAST	NM_014946.4	c.1111C>A	p.Leu371Ile	missense_variant	Exon 8 of 17	ENST00000315285.9	NP_055761.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SPAST	ENST00000315285.9	c.1111C>A	p.Leu371Ile	missense_variant	Exon 8 of 17	1	NM_014946.4	ENSP00000320885.3

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 6.86e-7 AC: 1 AN: 1457846 Hom.: 0 Cov.: 28 AF XY: 0.00 AC XY: 0 AN XY: 725522

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.0000299 AC: 1 AN: 33398

American (AMR) AF: 0.00 AC: 0 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26102

East Asian (EAS) AF: 0.00 AC: 0 AN: 39674

South Asian (SAS) AF: 0.00 AC: 0 AN: 86178

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53408

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1108356

Other (OTH) AF: 0.00 AC: 0 AN: 60246

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 31

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.56
BayesDel_addAF	Pathogenic	0.22	D
BayesDel_noAF	Uncertain	0.070
CADD	Pathogenic	27
DANN	Uncertain	0.99
DEOGEN2	Benign	0.35	T;T;.;.;.;.;.;.
Eigen	Uncertain	0.54
Eigen_PC	Uncertain	0.61
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.95	.;D;D;.;D;D;D;D
M_CAP	Uncertain	0.22	D
MetaRNN	Uncertain	0.60	D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.73	D
MutationAssessor	Uncertain	2.1	M;M;.;.;.;.;.;.
PhyloP100		7.4
PrimateAI	Pathogenic	0.80	T
PROVEAN	Benign	-1.9	N;.;N;.;.;.;.;.
REVEL	Uncertain	0.53
Sift	Uncertain	0.0050	D;.;D;.;.;.;.;.
Sift4G	Pathogenic	0.0	D;D;D;.;.;.;.;.
Polyphen		0.82	P;P;.;.;.;.;.;.
Vest4		0.57
MutPred		0.44		Gain of helix (P = 0.132);Gain of helix (P = 0.132);.;.;.;.;.;.;
MVP		0.67
MPC		2.3
ClinPred		0.97	D
GERP RS		5.7
Varity_R		0.87
gMVP		0.79
Mutation Taster		=18/82	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs1060499670; hg19: chr2-32352029;